1. The Field of the Invention
Only a fraction of the earth's total water supply is available and suitable for agriculture, industry and domestic needs. The demand for water is great and new technologies together with growing populations increase the demand for water while pollution diminishes the limited supply of usable water. The growing demand for water requires efficient use of available water resources.
Agricultural use of water places a large demand on the world's water supply. In some communities, the water supply may be adequate for farming but the quality of the water is unsuitable for agriculture because the water is alkaline. Alkalinity is an important factor affecting the quality, efficiency and performance of soil and irrigation water. A relative increase in irrigation alkalinity due to the water's sodium to calcium ratio or a high pH renders irrigation water detrimental to soil, crop growth and irrigation water efficiency. Such water can be reclaimed for soil rehabilitation and irrigation by adding lower pH sulphurous acid to the alkaline water to reduce its alkalinity or pH.
The invention of this application is directed toward a device which generates sulphurous acid in a simplified, efficient way. In particular, it is directed toward a sulphurous acid generator which produces sulphurous acid by burning sulphur to produce sulphur dioxide gas. The sulphur dioxide gas is then drawn toward and held in contact with water eventually reacting with the water and producing sulphurous acid, while substantially reducing dangerous emissions of sulphur dioxide gas to the air.
2. The Relevant Technology
There are several sulphurous acid generators in the art. The prior art devices utilize a variety of sulphur burn chambers and a variety of mechanisms for dissolving sulphur gases into water. However, many known systems utilize side-by-side hopper and burn chambers and/or countercurrent current flow, pressurized systems, and/or a single eductor arrangements as the principle means to accomplish the generation of sulphurous acid. For example, many devices employ the absorption tower to introduce the majority of the water to the system in countercurrent flow to the flow of sulphur dioxide gas. U.S. Pat. No. 4,526,771 teaches introducing 90% of the system water for the first time in countercurrent flow at the top of the absorption tower. In such devices, the integrity of the absorption towers is vital, and any deficiencies or inefficiencies of the absorption tower lead to diminished reaction and results. Other devices utilize pressurized gas to facilitate flow of gas through the system, see U.S. Pat. No. 3,226,201. Pressurized devices, however, require expensive manufacture to ensure the containment of dangerous sulphur dioxide gas to avoid leakage. Even negative pressure machines have the drawback of requiring a source of energy to power the negative pressure generator such as an exhaust fan. Still other devices rely upon secondary combustion chambers to further oxidize the sulphur, see U.S. Pat. No. 4,526,771. An earlier Harmon device utilized a single eductor in combination with a countercurrent absorption tower. The inventor has himself developed several different sulphur gas generators. U.S. Pat. Nos. 6,080,368, 6,248,299, 6,500,391, 6,506,347, and 6,689,326. Many sulphurous acid generators emit significant or dangerous levels of unreacted sulphur dioxide gas, a harmful and noxious pollutant, into the surrounding environment. Many devices discharge a visible plume or cloud.